scholarly journals Gas-Phase Pyrolysis Products Emitted by Prescribed Fires in Pine Forests with a Shrub Understory in the Southeastern United States

2019 ◽  
Author(s):  
Nicole K. Scharko ◽  
Ashley M. Oeck ◽  
Tanya L. Myers ◽  
Russell G. Tonkyn ◽  
Catherine A. Banach ◽  
...  
Keyword(s):  
Gas Phase ◽  
Pine Forests ◽  
Prescribed Fires ◽  
Pyrolysis Products ◽  
Prescribed Burns ◽  
Extraction Device ◽  
Dominant Process ◽  
Pyrolysis Gases ◽  
Manual Extraction ◽  
Emission Ratios

Abstract. In this study we capture and identify pyrolysis gases from prescribed burns conducted in pine forests with a shrub understory using a manual extraction device. The device selectively sampled emissions ahead of the flame front, minimizing collection of oxidized gases, with the captured gases analyzed in the laboratory using infrared absorption spectroscopy. Results show that emission ratios (ER) relative to CO for ethene, and acetylene were significantly greater than previous fire studies, suggesting that the sample device was able to collect gases prior to ignition. Further evidence that ignition had not begun was corroborated by novel infrared detections of several species, in particular naphthalene. With regards to oxygenated species, several aldehydes (acrolein, furaldehyde, acetaldehyde, formaldehyde) and the carboxylic acids (formic, acetic) were all observed; results show that ERs for acetaldehyde were noticeably greater while ERs for formaldehyde and acetic acid were lower compared to other studies. The acetylene-to-furan ratio also suggests that high temperature pyrolysis was the dominant process generating the collected gases. This hypothesis is further supported by the presence of HCN and the absence of NH3.

scholarly journals Gas-phase pyrolysis products emitted by prescribed fires in pine forests with a shrub understory in the southeastern United States

2019 ◽  
Vol 19 (15) ◽  
pp. 9681-9698 ◽  
Author(s):  
Nicole K. Scharko ◽  
Ashley M. Oeck ◽  
Tanya L. Myers ◽  
Russell G. Tonkyn ◽  
Catherine A. Banach ◽  
...  
Keyword(s):  
Pine Forests ◽  
Prescribed Fires ◽  
Ir Absorption ◽  
Pyrolysis Products ◽  
Prescribed Burns ◽  
Extraction Device ◽  
Dominant Process ◽  
Pyrolysis Gases ◽  
Manual Extraction ◽  
Emission Ratios

Abstract. In this study we identify pyrolysis gases from prescribed burns conducted in pine forests with a shrub understory captured using a manual extraction device. The device selectively sampled emissions ahead of the flame front, minimizing the collection of oxidized gases, with the captured gases analyzed in the laboratory using infrared (IR) absorption spectroscopy. Results show that emission ratios (ERs) relative to CO for ethene and acetylene were significantly greater than in previous fire studies, suggesting that the sample device was able to collect gases predominantly generated prior to ignition. Further evidence that ignition had not begun was corroborated by novel IR detections of several species, in particular naphthalene. With regards to oxygenated species, several aldehydes (acrolein, furaldehyde, acetaldehyde, formaldehyde) and carboxylic acids (formic, acetic) were all observed; results show that ERs for acetaldehyde were noticeably greater, while ERs for formaldehyde and acetic acid were lower compared to other studies. The acetylene-to-furan ratio also suggests that high-temperature pyrolysis was the dominant process generating the collected gases.

scholarly journals Identification of gas-phase pyrolysis products in a prescribed fire: first detections using infrared spectroscopy for naphthalene, methyl nitrite, allene, acrolein and acetaldehyde

2019 ◽  
Vol 12 (1) ◽  
pp. 763-776 ◽  
Author(s):  
Nicole K. Scharko ◽  
Ashley M. Oeck ◽  
Russell G. Tonkyn ◽  
Stephen P. Baker ◽  
Emily N. Lincoln ◽  
...  
Keyword(s):  
Gas Phase ◽  
Prescribed Fire ◽  
Wildland Fire ◽  
Pyrolysis Products ◽  
Prescribed Burns ◽  
Methyl Nitrite ◽  
Spectral Components ◽  
Volatile Organic ◽  
Pine Stands ◽  
Many Sources

Abstract. Volatile organic compounds (VOCs) are emitted from many sources, including wildland fire. VOCs have received heightened emphasis due to such gases' influential role in the atmosphere, as well as possible health effects. We have used extractive infrared (IR) spectroscopy on recent prescribed burns in longleaf pine stands and herein report the first detection of five compounds using this technique. The newly reported IR detections include naphthalene, methyl nitrite, allene, acrolein and acetaldehyde. We discuss the approaches used for detection, particularly the software methods needed to fit the analyte and multiple (interfering) spectral components within the selected spectral micro-window(s). We also discuss the method's detection limits and related parameters such as spectral resolution.

Changes in soil hydraulic conductivity after prescribed fires in Mediterranean pine forests

2019 ◽  
Vol 232 ◽  
pp. 1021-1027 ◽  
Author(s):  
P.A. Plaza-Álvarez ◽  
M.E. Lucas-Borja ◽  
J. Sagra ◽  
D.A. Zema ◽  
J. González-Romero ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Pine Forests ◽  
Prescribed Fires ◽  
Soil Hydraulic Conductivity ◽  
Soil Hydraulic ◽  
Mediterranean Pine

scholarly journals Characterization of PM2.5 collected during broadcast and slash-pile prescribed burns of predominately ponderosa pine forests in northern Arizona

2011 ◽  
Vol 45 (12) ◽  
pp. 2087-2094 ◽  
Author(s):  
Marin S. Robinson ◽  
Min Zhao ◽  
Lindsay Zack ◽  
Christine Brindley ◽  
Lillian Portz ◽  
...  
Keyword(s):  
Ponderosa Pine ◽  
Pine Forests ◽  
Prescribed Burns ◽  
Ponderosa Pine Forests ◽  
Northern Arizona

Transfer of elements to the atmosphere during low-intensity prescribed fires in three Australian subalpine eucalypt forests

1985 ◽  
Vol 15 (4) ◽  
pp. 657-664 ◽  
Author(s):  
R. J. Raison ◽  
P. K. Khanna ◽  
P. V. Woods
Keyword(s):  
Complete Recovery ◽  
Small Mass ◽  
Prescribed Fires ◽  
Prescribed Burns ◽  
Low Intensity ◽  
Percentage Loss ◽  
The Difference ◽  
High Concentrations ◽  
Eucalypt Forests ◽  
Shrub Biomass

Measurements were made of the transfer of N,P,K, Ca, Mg, Mn, and B to the atmosphere during low-intensity (350–600 kWm−1) prescribed burns in three Australian subalpine eucalypt forests dominated by overstoreys of either Eucalyptuspauciflora (Sieb. ex Spreng), Eucalyptusdives (Schau.), or Eucalyptusdelegatensis (R. T. Baker). Elemental transfer was calculated as the difference between the quantity of an element in the fuel (litter plus understorey) before burning and that present in the postfire residues which were recovered quantitatively using small aluminium trays. Complete recovery of fine ash is essential for accurate budgeting for elements other than N. The mass ranges of elements transferred to the atmosphere (kilograms per hectare) were as follows: N, 74–109; P, 1.96–3.04; K, 12.1–21.0; Ca, 18.7–29.7; Mg, 4.5–9.7; Mn, 1.6–4.3; B, 0.08–0.12. These transfers represented, as a percentage of the element initially present in the fuel, the following: N, 54–75; P, 37–50, K, 43–66; Ca, 31–34; Mg, 25–49; Mn, 25–43; B, 35–54. The percentage loss of elements was positively linearly correlated with the percentage loss in fuel weight. High concentrations of P and cations occur in fine ash, especially grey (mineral) ash. In comparison with unburnt litter, concentrations of Ca, Mg, and P were increased by 10- to 50-fold, 10- to 35-fold, and 10-fold in fine (<1 mm) ash produced at the E. pauciflora site, respectively. Hence, transport of a relatively small mass of fine ash either during or after a fire may result in the removal of a significant quantity of nutrients. Prescribed fire rotations of about 10–12 years are required in the forests studied to permit natural inputs of N to approximately replace the amounts transferred to the atmosphere in a single fire. For P replacement, rotation length would need to exceed 20 years. The major impact of regular burning would appear to be on the N cycle because of the rapid reaccumulation of N in shrub biomass and surface litter, thus rendering it highly susceptible to volatilization in a subsequent burn.

scholarly journals Soil Quality of Abandoned Agricultural Terraces Managed with Prescribed Fires and Livestock in the Municipality of Capafonts, Catalonia, Spain (2000–2017)

Agronomy ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 340 ◽  
Author(s):  
Xavier Úbeda ◽  
Meritxell Alcañiz ◽  
Gonzalo Borges ◽  
Luis Outeiro ◽  
Marcos Francos
Keyword(s):  
Soil Quality ◽  
Forest Fires ◽  
Prescribed Burning ◽  
Fire Hazard ◽  
Soil Conditions ◽  
Prescribed Fires ◽  
Agricultural Terraces ◽  
Prescribed Burns ◽  
The Impact ◽  
The Village

The abandonment of the economic activities of agriculture, livestock, and forestry since the second half of the 20th century, in conjunction with the exodus of inhabitants from rural areas, has resulted in an increase in the forest mass as well as an expansion of forest areas. This, in turn, has led to a greater risk of forest fires and an increase in the intensity and severity of these fires. Moreover, these forest masses represent a fire hazard to adjacent urban areas, which is a problem illustrated here by the village of Capafonts, whose former agricultural terraces have been invaded by shrubs, and which in the event of fire runs the risk of aiding the propagation of the flames from the forest to the village’s homes. One of the tools available to reduce the amount of fuel in zones adjoining inhabited areas is prescribed burns. The local authorities have also promoted measures to convert these terraces into pasture; in this way, the grazing of livestock (in this particular instance, goats) aims to keep fuel levels low and thus reduce the risk of fire. The use of prescribed fires is controversial, as they are believed to be highly aggressive for the soil, and little is known about their long-term effects. The alternation of the two strategies is more acceptable—that is, the use of prescribed burning followed by the grazing of livestock. Yet, similarly little is known about the effects of this management sequence on the soil. As such, this study seeks to examine the impact of the management of the abandoned terraces of Capafonts by means of two prescribed fires (2000 and 2002), which were designed specifically to prevent forest fires from reaching the village. Following these two prescribed burns, a herd of goats began to graze these terraces in 2005. Here, we report the results of soil analyses conducted during this period of years up to and including 2017. A plot comprising 30 sampling points was established on one of the terraces and used to monitor its main soil quality properties. The data were subject to statistical tests to determine whether the recorded changes were significant. The results show modifications to the concentration of soil elements, and since the first prescribed burn, these changes have all been statistically significant. We compare our results with those reported in other studies that evaluate optimum soil concentrations for the adequate growth of grazing to feed goats, and conclude that the soil conditions on the terrace after 17 years are optimum for livestock use.

scholarly journals Coupling field and laboratory measurements to estimate the emission factors of identified and unidentified trace gases for prescribed fires

2013 ◽  
Vol 13 (1) ◽  
pp. 89-116 ◽  
Author(s):  
R. J. Yokelson ◽  
I. R. Burling ◽  
J. B. Gilman ◽  
C. Warneke ◽  
C. E. Stockwell ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Proton Transfer ◽  
Gas Phase ◽  
Biomass Burning ◽  
Organic Soil ◽  
Emission Factors ◽  
Trace Gas ◽  
Prescribed Fires ◽  
Unidentified Species ◽  
Semiarid Shrubland

Abstract. An extensive program of experiments focused on biomass burning emissions began with a laboratory phase in which vegetative fuels commonly consumed in prescribed fires were collected in the southeastern and southwestern US and burned in a series of 71 fires at the US Forest Service Fire Sciences Laboratory in Missoula, Montana. The particulate matter (PM2.5) emissions were measured by gravimetric filter sampling with subsequent analysis for elemental carbon (EC), organic carbon (OC), and 38 elements. The trace gas emissions were measured by an open-path Fourier transform infrared (OP-FTIR) spectrometer, proton-transfer-reaction mass spectrometry (PTR-MS), proton-transfer ion-trap mass spectrometry (PIT-MS), negative-ion proton-transfer chemical-ionization mass spectrometry (NI-PT-CIMS), and gas chromatography with MS detection (GC-MS). 204 trace gas species (mostly non-methane organic compounds (NMOC)) were identified and quantified with the above instruments. Many of the 182 species quantified by the GC-MS have rarely, if ever, been measured in smoke before. An additional 153 significant peaks in the unit mass resolution mass spectra were quantified, but either could not be identified or most of the signal at that molecular mass was unaccounted for by identifiable species. In a second, "field" phase of this program, airborne and ground-based measurements were made of the emissions from prescribed fires that were mostly located in the same land management units where the fuels for the lab fires were collected. A broad variety, but smaller number of species (21 trace gas species and PM2.5) was measured on 14 fires in chaparral and oak savanna in the southwestern US, as well as pine forest understory in the southeastern US and Sierra Nevada mountains of California. The field measurements of emission factors (EF) are useful both for modeling and to examine the representativeness of our lab fire EF. The lab EF/field EF ratio for the pine understory fuels was not statistically different from one, on average. However, our lab EF for "smoldering compounds" emitted from the semiarid shrubland fuels should likely be increased by a factor of ~2.7 to better represent field fires. Based on the lab/field comparison, we present emission factors for 357 pyrogenic species (including unidentified species) for 4 broad fuel types: pine understory, semiarid shrublands, coniferous canopy, and organic soil. To our knowledge this is the most comprehensive measurement of biomass burning emissions to date and it should enable improved representation of smoke composition in atmospheric models. The results support a recent estimate of global NMOC emissions from biomass burning that is much higher than widely used estimates and they provide important insights into the nature of smoke. 31–72% of the mass of gas-phase NMOC species was attributed to species that we could not identify. These unidentified species are not represented in most models, but some provision should be made for the fact that they will react in the atmosphere. In addition, the total mass of gas-phase NMOC divided by the mass of co-emitted PM2.5 averaged about three (range ~2.0–8.7). About 35–64% of the NMOC were likely semivolatile or of intermediate volatility. Thus, the gas-phase NMOC represent a large reservoir of potential precursors for secondary formation of ozone and organic aerosol. For the single lab fire in organic soil about 28% of the emitted carbon was present as gas-phase NMOC and ~72% of the mass of these NMOC was unidentified, highlighting the need to learn more about the emissions from smoldering organic soils. The mass ratio of total NMOC to "NOx as NO" ranged from 11 to 267, indicating that NOx-limited O3 production would be common in evolving biomass burning plumes. The fuel consumption per unit area was 7.0 ± 2.3 Mg ha−1 and 7.7 ± 3.7 Mg ha−1 for pine-understory and semiarid shrubland prescribed fires, respectively.

An estimation of modelling parameters for condensed multi-component fuels

2011 ◽  
Vol 225 (5) ◽  
pp. 1229-1235
Author(s):  
V Raghavan ◽  
W T James ◽  
A S Rangwala
Keyword(s):  
Physical Properties ◽  
Ambient Pressure ◽  
Kinetics Parameters ◽  
Pyrolysis Products ◽  
Exponential Factor ◽  
Step Procedure ◽  
Global Reaction ◽  
Thermo Physical Properties ◽  
Pyrolysis Gases

A case study to evaluate the thermo-physical properties and chemical kinetics parameters, which are employed to model the gas-phase combustion taking place over the surface of a condensed fuel, has been presented. This procedure relies on accurate experimental measurements of gaseous pyrolysis products. The pyrolysis gases can be treated as a virtual fuel, namely C xH yO z, where x, y, and z are estimated by performing atom balances for C, H, and O atoms in all the pyrolysis species. Thermo-physical properties of this virtual fuel are calculated based on the temperature and species concentration of the pyrolysis mixture. Similarly, based on the rate constant values of the reactant species present in the pyrolysis mixture, Arrhenius parameters such as pre-exponential factor and activation energy have been calculated. Polymethylmethacrylate (PMMA) is used as an example fuel in this study, and a step-by-step procedure for the estimation of the thermo-physical properties and global reaction kinetics parameters of PMMA at low to moderate ambient pressure environment is presented. In general, the technique discussed here can be applied to any condensed fuel. Following the procedure reported in this study, modelling parameters can be evaluated for complex fuels.

scholarly journals Gaseous Products from Scrap Tires Pyrolisis

2012 ◽  
Vol 19 (3) ◽  
pp. 451-460 ◽  
Author(s):  
Katarzyna Januszewicz ◽  
Marek Klein ◽  
Ewa Klugmann-Radziemska
Keyword(s):  
European Union ◽  
Gas Chromatography ◽  
Common Method ◽  
Pyrolysis Process ◽  
Pyrolysis Products ◽  
Scrap Tires ◽  
Gaseous Products ◽  
Oil Fractions ◽  
Light Oil ◽  
Pyrolysis Gases

Gaseous Products from Scrap Tires Pyrolisis In European Union 75% of used tires should be recycled. The most common method of used tires disposal, is burning in cement kilns, which does not solve the problem. Pyrolysis process can be an alternative way of utilization of tires. The aim of the researches was to check the influence of pyrolysis products (gas and oil fractions) on environment. Samples from pyrolysis process, like light oil fractions or pyrolysis gases were analyzed using gas chromatography. The pyrolysis installation should be hermetical, because of the PAHs which were detected in a light fraction of oil. In exhaust gases BTEX and PAHs were not detected.

scholarly journals Development and Analysis of the Physicochemical and Mechanical Properties of Diorite-Reinforced Epoxy Composites

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2421
Author(s):  
Amirbek Bekeshev ◽  
Anton Mostovoy ◽  
Yulia Kadykova ◽  
Marzhan Akhmetova ◽  
Lyazzat Tastanova ◽  
...  
Keyword(s):  
Gas Phase ◽  
Thermal Destruction ◽  
Epoxy Polymer ◽  
Epoxy Composite ◽  
Chemical Interaction ◽  
Strength Properties ◽  
Epoxy Composites ◽  
Mineral Filler ◽  
Pyrolysis Products ◽  
Thermal Stability Of

The aim of this paper is to study the effect of a polyfunctional modifier oligo (resorcinol phenyl phosphate) with terminal phenyl groups and a dispersed mineral filler, diorite, on the physicochemical and deformation-strength properties of epoxy-based composites. The efficiency of using diorite as an active filler of an epoxy polymer, ensuring an increase in strength and a change in the physicochemical properties of epoxy composites, has been proven. We selected the optimal content of diorite both as a structuring additive and as a filler in the composition of the epoxy composite (0.1 and 50 parts by mass), at which diorite reinforces the epoxy composite. It has been found that the addition of diorite into the epoxy composite results in an increase in the Vicat heat resistance from 132 to 140–188 °C and increases the thermal stability of the epoxy composite, which is observed in a shift of the initial destruction temperature to higher temperatures. Furthermore, during the thermal destruction of the composite, the yield of carbonized structures increases (from 54 to 70–77% of the mass), preventing the release of volatile pyrolysis products into the gas phase, which leads to a decrease in the flammability of the epoxy composite. The efficiency of the functionalization of the diorite surface with APTES has been proven, which ensures chemical interaction at the polymer matrix/filler interface and also prevents the aggregation of diorite particles, which, in general, provides an increase in the strength characteristics of epoxy-based composite materials by 10–48%.

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